Preservation of the viability of donor organs is an important goal for organ transplantation. Typically the organ to be transplanted must be stored and shipped to the prospective recipient. The ability to prolong the cellular viability of the organ during storage and transportation is very important to the success of the transplant operation. Preservative solutions play an important role in the longevity of the organ. Solutions for organ preservation include those described by Berdyaev et al., U.S. Pat. No. 5,432,053; Belzer et al., U.S. Pat. Nos. 4,798,824, 4,879,283, and 4,873,230; Taylor, U.S. Pat. No. 5,405,742; Dohi et al., U.S. Pat. No. 5,565,317; Stern et al., U.S. Pat. Nos. 5,370,989 and 5,552,267, the contents of which are incorporated herein by reference in their entirety. However, a need exists for improved methods and solutions for organ preservation.
Proteases are involved in a broad range of biological pathways. In particular, serine proteases such as kallikrein, plasmin, elastase, urokinase plasminogen activator, thrombin, human lipoprotein-associated coagulation inhibitor, and coagulation factors such as factors VIIa, IXa, Xa, XIa, and XIIa have been implicated in pathways affecting blood flow, e.g., general and focal ischemia, tumor invasion, fibrinolysis, perioperative blood loss, and inflammation. Inhibitors of specific serine proteases, therefore, have received attention as potential drug targets for various ischemic maladies.
One such inhibitor, aprotinin (also called bovine pancreatic trypsin inhibitor or BPTI), obtained from bovine lung, has been approved in the United States for prophylactic use in reducing perioperative blood loss and the need for transfusion in patients undergoing CPB, e.g., in the course of a coronary artery bypass grafting procedure. Aprotinin is commercially available under the trade name TRASYLOL® (Bayer Corporation Pharmaceutical Division, West Haven, Conn.) and was previously approved for use to treat pancreatitis. The effectiveness of aprotinin is associated with its relatively non-specific abilities to inhibit a variety of serine proteases, including plasma kallikrein, and plasmin. These proteases are important in a number of pathways of the contact activation system (CAS).
CAS is initially activated when whole blood contacts the surface of foreign substrates (e.g., kaolin, glass, dextran sulfate, or damaged bone surfaces). Kallikrein, a serine protease, is a plasma enzyme that initiates the CAS cascade leading to activation of neutrophils, plasmin, coagulation, and various kinins. Kallikrein is secreted as a zymogen (pre-kallikrein) that circulates as an inactive molecule until activated by a proteolytic event early in the contact activation cascade.
However, the use of specific kallikrein inhibitors for organ preservation has not been successfully demonstrated.